Update synapse to version v1.148.0

[al-lac]

🤖 This is an automated pull request to update synapse to version v1.148.0. This PR must be reviewed and tested before merging.

Auto-generated update considerations:

• Security fix in v1.147.1 blocks federation requests authenticated with known insecure signing keys (CVE-2026-24044); upgrading promptly is strongly recommended to avoid potential federation abuse.
• MSC3244 (Room version capabilities) support has been removed in v1.148.0; any configuration or experimental flags referencing this MSC should be reviewed and cleaned up to avoid unexpected behavior.
• Docker images are now also pushed to the Element OCI Registry in v1.148.0; if any custom Docker Compose configurations reference image sources explicitly, verify the correct registry is still being used.

Original GitHub release notes

[github-actions]

🎉   Linting finished with no errors or warnings   🎉

Thank you for your submission! This is an automated linter that checks for common issues in pull requests to the Umbrel App Store.

[al-lac]

🤖 This is an automated summary of installation tests for synapse:

• ✅ App successfully installed in umbrel-dev instance
• ✅ App successfully listed in umbrel.yaml
• ✅ App UI successfully returns a 200 status code
• 📸 Screenshot of the app:
  

This PR must still be reviewed and tested before merging.

[al-lac]

Tested update on Umbrel dev instance.